Вправа 1091 алгебра Бевз гдз 7 клас
№ 1091 $$\begin{aligned}
& \text { a) }\left\{\begin{array}{c}
4(x+2 y)=5 x+6 \\
3(2 x-y)=24 y+6
\end{array}\right. \\
& \left\{\begin{array}{c}
4 x+8 y=5 x+6 \\
6 x-3 y=24 y+6
\end{array}\right. \\
& \left\{\begin{array}{c}
x=8 y-6 \\
6 \cdot(8 y-6)=27 y+6
\end{array}\right.
\end{aligned}
$$
$$
\begin{aligned}
& 48 y-36-27 y=6 \\
& 21 y=6+36 \\
& 21 y=42 \\
& y=2 \\
& x=8 \cdot 2-6 \\
& x=16-6 \\
& x=10
\end{aligned}
$$
Відповідь: (10; 2) $$
\begin{aligned}
& \text { б) }\left\{\begin{array}{c}
5(x-3 y)=2 x+7 \\
3(x+6 y)=9 y+15 ;
\end{array}\right. \\
& \left\{\begin{array}{l}
5 x-15 y=2 x+7, \\
3 x+18 y=9 y+15 ;
\end{array}\right. \\
& \left\{\begin{array}{c}
5 x-2 x-15 y=7 ; \\
3 x+18 y-9 y=15 ;
\end{array}\right. \\
& \left\{\begin{array}{l}
3 x-15 y=7 \\
3 x+9 y=15 ;
\end{array}\right. \\
& \left\{\begin{array}{l}
3 x-15 y=7 \\
3 x=15-9 y ;
\end{array}\right. \\
& \left\{\begin{array}{c}
x=5-3 y \\
3 \cdot(5-3 y)-15 y=7 ;
\end{array}\right. \\
& 15-9 y-15 y=7
\end{aligned}
$$
$$
\begin{aligned}
& -24 y=7-15 \\
& y=-8:(-24) \\
& y=\frac{1}{3} \\
& x=5-3 \cdot \frac{1}{3} \\
& x=5-1 \\
& x=4 \\
& \text { Відповідь: }\left(4 ; \frac{1}{3}\right)
\end{aligned}
$$
вправи поруч
